Resist stripper system

ABSTRACT

A system for removing photoresist and providing in-situ discharge. A resist stripper system includes a vertical downstream chamber, a gas passageway at the top of the vertical downstream chamber to supply an inert gas, and a wafer plate at the bottom inside the vertical downstream chamber to support and fix a wafer. A plasma generating system on the vertical downstream chamber near the gas passageway induces plasma of an inert gas. A first gas outlet on the vertical downstream chamber between the wafer plate and the plasma generating system exhausts the plasma, and a second gas outlet on the vertical downstream chamber beneath the wafer plate exhausts resist residue. A power supply is connected to the wafer plate to apply a positive bias to the wafer to attract electrons.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a semiconductor fabrication device and in particular to a resist stripper system capable of in-situ discharge of electrons from the semiconductor wafer while removing photoresist with plasma.

[0003] 2. Description of the Related Art

[0004] Semiconductor fabrication forms integrated circuits and semiconductor devices on the surface of a silicon wafer. Accordingly, various conductors, semiconductors, insulators, and ion doped areas are formed by way of photolithography with corresponding masks to define patterns on the wafer. Since photoresist is applied on the surface of the wafer, it is necessary to etch certain areas of, or strip the entire photoresist layer.

[0005] Photoresist layer can be removed by wet etching, in which the photoresist is stripped with solvents or oxidant reagents, or by dry etching, which uses large amounts of oxygen-containing plasma to remove photoresist by chemical ion bombardment. The dry etching is usually conducted in a vertical downstream resist stripper system. A conventional vertical downstream resist stripper system comprises a reactive chamber, a wafer plate to support the wafer, gas pipelines connected to the chamber, a plasma generating system, and gas pipelines to import reactive gases, such as oxygen, ammonia, nitrogen or combinations thereof, into the reactive chamber. The plasma generating system induces plasma of the gas to react with the resist layer and form resist residue, and gas outlets are connected to a pump to remove resist residue.

[0006] However, a disadvantage of the conventional vertical downstream resist stripper system is that charges accumulate on the wafer surface after the resist has been stripped. The remaining charges may accelerate the corrosion of tungsten on the wafer, and thus downgrade the reliability of the integrated circuits or semiconductors thereon.

SUMMARY OF THE INVENTION

[0007] Accordingly, an object of the invention is to provide a vertical downstream resist stripper system that is capable of in-situ discharge of a wafer while stripping resist therefrom, avoiding potential damage caused by charges.

[0008] To achieve the above object, the present invention provides a vertical downstream resist stripper system, including a vertical downstream chamber, a gas passageway at the top of the vertical downstream chamber to supply an inert gas, a plasma generating system installed on the vertical downstream chamber near the gas passageway to induce plasma, a wafer plate at the bottom inside the vertical downstream chamber to support and fix a wafer, a first gas outlet on the vertical downstream chamber between the wafer plate and the plasma generating system, exhausting the plasma byproduct, a second gas outlet on the vertical downstream chamber beneath the wafer, plate, exhausting resist residue, and a power supply to apply a positive bias to the wafer to attract electrons.

[0009] Moreover, the gas passageway of the stripper system further supplies a resist stripping gas to the vertical downstream chamber. In addition to high molecular weight inert gas, the gas passageway also supplies gases that react with the resist to perform oxidation, such as oxygen (O₂), ammonium (NH₃), nitrogen (N₂) or combinations thereof.

[0010] Preferably, the frequency of the plasma generating system is radio frequency (RF) or microwave generated by a high frequency power.

[0011] Preferably, the gas supplied the electron flushing system in the vertical chamber is the high molecular weight of inert gases such as Argon or Xenon, which can insert with other molecules, thereby improving flushing of the plasma stream from the chamber.

[0012] Moreover, the vertical downstream resist stripper system further comprises a first pipeline connected to the first gas outlet and a gas valve coupled to the first pipeline to control the plasma byproduct exhaust from the first gas outlet.

[0013] Furthermore, the vertical downstream resist stripper system also comprises a second pipeline connected to the second gas outlet and a gas valve on the second pipeline to control resist residue exhaust from the second gas outlet.

[0014] Moreover, the first pipeline can be connected to the second pipeline with a connection point. A pump is coupled to the downstream of the connection point to accelerate exhaust of the ionic plasma and resist residue from the chamber.

[0015] Preferably, the power supply, e.g. a DC supplier, is coupled to the wafer plate to apply positive bias on the wafer to attract electrons and discharge the positive charge from the surface of the wafer.

[0016] A detailed description is given in the following embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

[0018]FIG. 1 is schematic side view of a vertical downstream resist stripper system according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0019]FIG. 1 illustrates a vertical downstream resist stripper system 100 according to one embodiment of the present invention.

[0020] In FIG. 1, the vertical downstream resist stripper system 100 includes a vertical downstream chamber 10 that can be cylindrical. A gas passageway 12 at the top of the vertical downstream chamber 10 introduces high molecular weight inert gas A, such as Argon (Ar) or Xenon (Xe), and reactive stripper gases B, such as oxygen, nitrogen, water vapor, carbon tetrafluoride (CF₄) ammonium (NH₃) or combinations thereof, into the chamber 10. A plasma generating system 14 is installed on the chamber 10 beneath the gas passageway 12. Preferably, the plasma generating system 14 is a high frequency power supply that can generate radio frequency (RF) or microwave to induce plasma C of the gases A and B. The plasma generally contains electrons, ions, radicals and molecules.

[0021] A wafer plate 16 or wafer holder is placed in the bottom of the vertical chamber 10 of the vertical downstream resist stripper system 100 to support and fix a wafer 18 with a resist layer thereon.

[0022] The vertical downstream resist stripper system 100 further includes a power supply, such as a DC supplier 32, connected to the wafer plate 16 to apply a positive bias to the wafer 18, neutralizing charges thereon. That is, charges generated on the wafer 18 during resist stripping are in-situ discharged.

[0023] Preferably, the vertical downstream resist stripper system 100 further includes first gas outlet 20 located between the wafer plate 16 and the plasma generating system 14 to exhaust plasma from the vertical chamber 10. More specifically, the first gas outlet 20 is connected to the first pipeline 22 to exhaust the plasma. A first gas valve 24 on the first gas outlet 20 manipulates the passage or exhaust rate of the plasma. The plasma C is easily exhausted from the vertical chamber 10 due to the presence of non-reactive and high molecular weight inert gas.

[0024] Preferably, the vertical downstream resist stripper system 100 further includes second gas outlet 26 at the bottom of the chamber 10 and beneath the wafer plate 16 to exhaust the resist residue D. More specifically, the second gas outlet 26 is connected to the second pipeline 28. A second gas valve 30 on the second pipeline 28 can control the passage or exhaust rate of the resist residue D. Accordingly, the resist residue D can be easily exhausted from the chamber 10 due to the presence of high molecular weight inert gas.

[0025] Preferably, the first and second pipelines 22 and 28 are connected together and a pump 40 is installed on the downstream of the connected point to accelerate the exhausting of the ionic plasma C and resist residue D from the chamber 10.

[0026] Preferably, when the valve 30 of the PR striper is opened, the electron flush will open the valve 24. The first and second gas valve 24 and 30 won't open at the same time to operate the PR striper and electron flushing system. Only one of the gas valves 24 or 30 can open after which the other can open.

[0027] Accordingly, the system of the present invention provides a power supply 32 to apply a positive bias to the wafer plate 16 and thus in-situ discharge the wafer on the wafer plate. The charges accumulated on the wafer during resist stripping are in-situ discharged and therefore cannot damage the semiconductors in subsequent process.

[0028] Accordingly, the system of the present invention provides two gas outlets with gas valves to facilitate the passage and flow rate of the ionic plasma and resist residue.

[0029] While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. 

What is claimed is:
 1. A resist stripper system, comprising: a vertical downstream chamber; a gas passageway at the top of the vertical downstream chamber to supply an inert gas; a plasma generating system installed on the vertical downstream chamber near the gas passageway to induce plasma; a wafer plate at the bottom inside the vertical downstream chamber to support and fix a wafer; a first gas outlet on the vertical downstream chamber between the wafer plate and the plasma generating system, exhausting the plasma; a second gas outlet on the vertical downstream chamber beneath the wafer plate, exhausting photoresist residue; and a power supply to apply a positive bias to the wafer to attract electrons.
 2. The system as claimed in claim 1, wherein the gas passageway further supplies a resist stripping gas to the vertical downstream chamber.
 3. The system as claimed in claim 1, wherein the frequency of the plasma generating system is radio frequency (RF) or microwave.
 4. The system as claimed in claim 1, wherein the inert gas is Argon (Ar).
 5. The system as claimed in claim 1, wherein the inert gas is Xenon (Xe).
 6. The system as claimed in claim 1, further comprising a first pipeline connected to the first gas outlet.
 7. The system as claimed in claim 6, further comprising a first gas valve coupled to the first pipeline to control plasma exhaust from the first gas outlet.
 8. The system as claimed in claim 7, wherein only one of the first and second gas valves can open after which the other can open.
 9. The system as claimed in claim 7, further comprising a second pipeline connected to the second gas outlet.
 10. The system as claimed in claim 9, further comprising a second gas valve coupled to the second pipeline to control photoresist exhaust from the second gas outlet, wherein the second pipeline is connected to the first pipeline.
 11. The system as claimed in claim 10, further comprising a pump on the downstream of the connection point of the first and second pipelines.
 11. The system as claimed in claim 10, wherein only one of the first and second gas valves can open after which the other can open.
 12. The system as claimed in claim 1, wherein the power supply is electrically connected to the wafer plate. 